Orthopaedic sensor module and system for determining joint forces of a patient&#39;s knee joint

ABSTRACT

An orthopaedic surgical device for determining the joint force of a patient&#39;s knee joint includes a tibial paddle shaped to be positioned in the patient&#39;s knee joint and a handle extending from the tibial paddle. The tibial paddle includes a sensor array positioned therein and configured to generate sensor signals indicative of the joint force of the patient&#39;s knee joint. The orthopaedic surgical device also includes a control circuit configured to control a display located on the handle to provide a visual indication of the medial and lateral balance of the joint force. In some embodiments, various tibial trialing components may be coupled to the tibial paddle along with an associated adaptor.

CROSS-REFERENCE TO RELATED U.S. PATENT APPLICATION

Cross-reference is made to U.S. Utility patent application Ser. No. ______, entitled “ORTHOPAEDIC SURGICAL SYSTEM FOR DETERMINING JOINT FORCES OF A PATIENT'S KNEE JOINT,” by Jason T. Sherman (DEP6414USNP; 265280-217043), which was filed on Mar. 31, 2012; to U.S. Utility patent application Ser. No. ______, entitled “SYSTEM AND METHOD FOR VALIDATING AN ORTHOPEDIC SURGICAL PLAN,” by Jason T. Sherman (DEP6234USNP; 265280-208915), which was filed on Mar. 31, 2012; to U.S. Utility patent application Ser. No. 12/415,225 entitled “DEVICE AND METHOD FOR DISPLAYING JOINT FORCE DATA” by Jason T. Sherman, which was filed on Mar. 31, 2009; to U.S. Utility patent application Ser. No. 12/415,290 entitled “METHOD FOR PERFORMING AN ORTHOPAEDIC SURGICAL PROCEDURE” by Mick Rock, which was filed on Mar. 31, 2009; to U.S. Utility patent application Ser. No. 12/415,172 entitled “DEVICE AND METHOD FOR DETERMINING FORCES OF A PATIENT'S JOINT” by Jason T. Sherman, which was filed on Mar. 31, 2009; to U.S. Utility patent application Ser. No. 12/415,365 entitled “SYSTEM AND METHOD FOR DISPLAYING JOINT FORCE DATA” by Jason Sherman, which was filed on Mar. 31, 2009; and to U.S. Utility patent application Ser. No. 12/415,350, entitled “DEVICE AND METHOD FOR DETERMINING FORCES OF A PATIENT'S KNEE JOINT” by Jason T. Sherman, which was filed on Mar. 31, 2009; the entirety of each of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to orthopaedic surgical instruments and, more particularly, to systems, devices, and methods for determining and displaying joint force data.

BACKGROUND

Orthopaedic prostheses are implanted in patients by orthopaedic surgeons to, for example, correct or otherwise alleviate bone and/or soft tissue loss, trauma damage, and/or deformation of the bone(s) of the patients. Orthopaedic prostheses may replace a portion or the complete joint of a patient. For example, the orthopaedic prosthesis may replace the patient's knee, hip, shoulder, ankle, or other joint. In the case of a knee replacement, the orthopaedic knee prosthesis may include a tibial tray, a femoral component, and a polymer insert or bearing positioned between the tibial tray and the femoral component. In some cases, the knee prosthesis may also include a prosthetic patella component, which is secured to a posterior side of the patient's surgically-prepared patella.

During the orthopaedic surgical procedure, a surgeon initially prepares the patient's bone(s) to receive the orthopaedic prosthesis. For example, in the case of a knee replacement orthopaedic surgical procedure, the surgeon may resect a portion of the patient's proximal tibia to which the tibia tray will be attached, a portion of patient's distal femur to which the femoral component will be attached, and/or a portion of the patient's patella to which the patella component will be attached. During such procedures, the surgeon may attempt to balance or otherwise distribute the joint forces of the patient's joint in order to produce joint motion that is similar to the motion of a natural joint. To do so, the surgeon may use surgical experience and manually “feel” for the appropriate joint force balance. Additionally or alternatively, the orthopaedic surgeon may use surgical instruments, such as a ligament balancer in the case of a knee replacement procedure, to assist in the balancing or distributing of joint forces.

In addition, in some surgical procedures such as minimally invasive orthopaedic procedures, surgeons may rely on computer assisted orthopaedic surgery (CAOS) systems to improve the surgeon's ability to see the operative area, to improve alignment of bone cut planes, and to improve the reproducibility of such cut planes. Computer assisted orthopaedic surgery systems assist surgeons in the performance of orthopaedic surgical procedures by, for example, displaying images illustrating surgical steps of the surgical procedure being performed and rendered images of the relevant bones of the patient. Additionally, computer assisted orthopaedic surgery (CAOS) systems provide surgical navigation for the surgeon by tracking and displaying the position of the patient's bones, implants, and/or surgical tools.

SUMMARY

According to one aspect, an orthopaedic surgical device for measuring a joint force of a patient's joint may include a tibial paddle shaped to be positioned between a patient's proximal tibia and distal femur, a sensor array positioned in the tibial paddle, an elongated handle secured to the tibial paddle and defining a longitudinal axis that is offset from an anterior-to-posterior bisecting axis of the tibial paddle, a first display secured to an end of the handle distal from the tibial paddle, and a circuit positioned in the handle. The tibial paddle may have a substantially planar upper surface and a substantially planar bottom surface. The sensor array may be configured to generate sensor signals indicative of a joint force between the patient's tibia and femur. In some embodiments, the sensor array may include a plurality of medial-anterior sensors to measure a medial-anterior force component of the joint force, a plurality of medial-posterior sensors to measure a medial-posterior force component of the joint force, a plurality of lateral-anterior sensors to measure a lateral-anterior force component of the joint force, and a plurality of lateral-posterior sensors to measure a lateral-posterior force component of the joint force. Additionally, in some embodiments, each of the medial-anterior sensors and lateral-anterior sensors may have a substantially equal surface area, and each of the medial-posterior sensors and lateral-posterior sensors having a substantially equal surface area. The circuit may be configured to receive the sensor signals from the sensor array and to control the display to provide a visual indication of the medial-lateral balance of the joint force.

In some embodiments, the tibial paddle may include a top paddle housing having a first inner sidewall that defines a first centrally-located aperture and a bottom paddle housing having a second inner sidewall that defines a second centrally-located aperture. In such embodiments, the first aperture and second aperture may be in fluid communication with each other to define, in part, a vertical passageway through the tibial paddle relative to the upper and bottom surfaces of the tibial paddle. Additionally, in such embodiments, the sensor array may include a centrally located aperture that further defines the vertical passageway through the tibial paddle.

The some embodiments, the sensor array may include a plurality of capacitive pressure sensors. Additionally, the sensor array may include of a medial set of sensors and a lateral set of sensors. In such embodiments, each of the medial set and lateral set of sensors may consist of an anterior-most sensor, a posterior-most sensor, and four additional sensors located between the corresponding anterior-most sensor and posterior-most sensor. Additionally, in some embodiments, the surface area of each of the medial-anterior and lateral-anterior sensors is less than the surface area of each of the medial-posterior and lateral-posterior sensors. For example, in one particular embodiment, each of the medial-anterior and lateral-anterior sensors has a surface area equal to about 0.174 in² and each of the medial-posterior and lateral-posterior has a surface area equal to about 0.187 in². In another particular embodiment, each of the medial-anterior and lateral-anterior sensors has a surface area equal to about 0.243 in² and each of the medial-posterior and lateral-posterior has a surface area equal to about 0.263 in².

In some embodiments, the orthopaedic surgical device may further include a second display secured to the end of the elongated handle distal from the tibial paddle. In such embodiments, the elongated handle may include a top handle housing and a bottom handle housing. The top and bottom handle housings may be coupled to each other such that an interior surface of the top handle housing faces a corresponding interior surface of the bottom handle housing. Additionally, the first display may be secured to an end of the top handle housing and the second display may be secured to an end of the bottom handle housing.

Additionally, in some embodiments, the first display may include a plurality of light emitting diodes and the circuit may be configured to (i) determine a total medial force value indicative of a medial component of the joint force, (ii) determine a total lateral force value indicative of a lateral component of the joint force, and (iii) control the plurality of light emitting diodes in a manner to provide an indication of the medial-lateral balance of the joint force. Additionally, the circuit may be configured to control the plurality of light emitting diodes to display at least nine separate illumination configurations corresponding to nine separate medial-lateral balance ranges. The circuit may further be configured to sum the total medial force value and the total lateral force value to determine a total force value, determine a medial percentage value as a function of the total medial force value and the total force value, determine a lateral percentage value as a function of the total lateral force value and the total force value, and control the plurality of light emitting diodes in a manner to provide an indication of the medial-lateral balance of the joint force as a function of the medial percentage value and the lateral percentage value.

In some embodiments, the circuit may include a wireless transmitter configured to transmit data indicative of the joint force between the patient's tibia and femur. Additionally, in some embodiments the circuit may include a power source and a user control operative to place the circuit into an on-state from an off-state. In such embodiments, the circuit may be configured to remain in the on-state after being placed in the on-state from the off-state until the power source is depleted.

According to another aspect, a sensor module to measure a joint force of a patient's joint may include an upper housing and a lower housing. The upper housing may include an upper handle housing and an upper tibial paddle housing. Similarly, the lower housing may include a lower handle housing and a lower tibial paddle housing. The lower housing may be coupled to the upper housing such that an interior surface of the lower housing faces a corresponding interior surface of the upper housing. The sensor module may further include a sensor array positioned between the lower tibial paddle housing and the upper tibial paddle housing. The sensor array may be configured to generate sensor signals indicative of a joint force between the patient's tibia and femur. The sensor array may include a plurality of anterior sensors to measure an anterior force component of the joint force and a plurality of posterior sensors to measure a posterior component of the joint force. Each of the posterior sensors may have a surface area that is greater than each of the anterior sensors.

The sensor module may further include a first display secured to the upper handle housing and a second display secured to the lower handle housing. Additionally, the sensor module may include a circuit positioned between the upper handle housing and the lower handle housing. The circuit may be configured to receive the sensor signals from the sensor array and to control the first and second displays to illuminate in one of a plurality of illumination configurations. Each illumination configurations may correspond to a separate range of medial-lateral balance of the joint force.

In some embodiments, the upper tibial housing and the lower tibial housing may each include an inner sidewall that defines a centrally located aperture. The inner sidewalls of the upper and lower tibial housings may cooperate to define a passageway when the upper housing is coupled to the lower housing. Additionally, in some embodiments, the sensor array comprises of a medial set of sensors and a lateral set of sensors. Each of the medial set and lateral set of sensors may include of an anterior-most sensor, a posterior-most sensor, and four additional sensors located between the corresponding anterior-most sensor and posterior-most sensor.

Additionally, in some embodiments, the circuit may be configured to control the first and second displays to display one of at least nine separate illumination configurations. Each illumination configuration may correspond to a separate range of medial-lateral balance of the joint force. In some embodiments, the circuit may further include a wireless transmitter configured to transmit data indicative of the joint force between the patient's tibia and femur. Additionally, in some embodiments, the circuit may include a power source and a user control operative to place the circuit into an on-state from an off-state. In such embodiments, the circuit may be configured to remain in the on-state after being placed in the on-state from the off-state until the power source is depleted.

According to a further aspect, an orthopaedic surgical system for measuring a joint force of a patient's joint may include a sensor module and a hand-held display module. The sensor module may include a tibial paddle, a sensor array positioned in the tibial paddle, an elongated handle secured to the tibial paddle, a first display secured to the handle, and a sensor module circuit positioned in the handle. The tibial paddle may be shaped to be positioned between a patient's proximal tibia and distal femur. Additionally, the tibial paddle may have a substantially planar upper surface and a substantially planar bottom surface and include an inner sidewall that defines a vertical passageway through the tibial paddle relative to the upper and bottom surfaces. The sensor array may be configured to generate sensor signals indicative of a joint force between the patient's tibia and femur. The sensor array may include a plurality of medial-anterior sensors to measure a medial-anterior force component of the joint force, a plurality of medial-posterior sensors to measure a medial-posterior force component of the joint force, a plurality of lateral-anterior sensors to measure a lateral-anterior force component of the joint force, and a plurality of lateral-posterior sensors to measure a lateral-posterior force component of the joint force. In such embodiments, each of the medial-anterior sensors and lateral-anterior sensors may have a substantially equal surface area, and each of the medial-posterior sensors and lateral-posterior sensors may have a substantially equal surface area. The sensor module circuit may be configured to receive the sensor signals from the sensor array, control the display to provide a visual indication of the medial-lateral balance of the joint force, and transmit the joint force data indicative of the joint force.

The hand-held display module may include a housing sized to be hand-holdable, a display coupled to the housing, and a control circuit positioned in the housing. The control circuit may be configured to receive the joint force data from the sensor module and display a visual indication of the medial-lateral balance of the joint force on the display of the hand-held display module. In some embodiments, the control circuit of the hand-held display module may be configured to display a horizontal bar on the display of the hand-held display module and display an icon on the horizontal bar. The position of the icon on the horizontal bar may be indicative of the medial-lateral balance of the joint force. Additionally, in some embodiments, the control circuit of the hand-held display module may be configured to determine a joint force value indicative of the medial-lateral balance and the anterior-posterior balance of the joint force and display a visual indication on the display of the medial-lateral and the anterior-posterior balance of the joint force based on the joint force value. Additionally, the control circuit of the hand-held display module may be configured to display a bar on the display. The bar may have a first end corresponding to a medial side and a second end corresponding to a lateral side. As such, the control circuit may be configured to position the first and second ends of the bar based on the anterior-posterior balance of the joint force.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures, in which:

FIG. 1 is a simplified diagram of one embodiment of a system for measuring and displaying joint force data of a patient's joint;

FIG. 2 is a perspective view of one embodiment of a sensor module of the system of FIG. 1;

FIG. 3 is a plan view of a top side of the sensor module of FIG. 2;

FIG. 4 is a plan view of a bottom side of the sensor module of FIG. 2;

FIG. 5 is an exploded, perspective view of the sensor module of FIG. 2;

FIG. 6 is an elevation view of a handle end of the sensor module of FIG. 2;

FIG. 7 is a graph of one embodiment of an illumination configuration display protocol for displays of the sensor module of FIG. 2;

FIG. 8 is a simplified diagram of one embodiment of a sensor array of the sensor module of FIG. 2;

FIG. 9 is a simplified block diagram of one embodiment of an electrical circuit of the sensor module of FIG. 2;

FIG. 10 is a simplified flow diagram of one embodiment of a method for determining and displaying joint force data that may be executed by the sensor module of FIG. 2;

FIG. 11 is a simplified flow diagram of one embodiment of a method for displaying relative joint force data that may be executed by the sensor module of FIG. 2;

FIG. 12 is a perspective view of one embodiment of a display module of the system of FIG. 1;

FIG. 13 is a plan view of the display module of FIG. 12;

FIG. 14 is a simplified block diagram of one embodiment of an electrical circuit of the display module of FIG. 12;

FIG. 15 is a simplified flow diagram of one embodiment of a method for displaying joint force data that may be executed by the display module of FIG. 12;

FIGS. 16-18 are illustrative screenshots that may be displayed to a user on the display module of FIG. 12;

FIG. 19 is a perspective view of one embodiment of a trialing system using the sensor module of FIG. 2;

FIGS. 20A-20E are perspective views of an adaptor of the system of FIG. 19;

FIG. 21 is a perspective view of the adaptor of FIG. 20 coupled to the sensor module of FIG. 2;

FIG. 22 is a cross-sectional view of the adapter and sensor module of FIG. 21;

FIG. 23 is a top plan view of a spacer block of FIG. 19 coupled to the sensor module and adaptor of FIG. 21 in a non-rotating orientation;

FIG. 24 is a top plan view of the spacer block of FIG. 23 coupled to the sensor module and adaptor of FIG. 21 in a rotating orientation and rotated to a maximum rotation position;

FIG. 25 is a top plan view of the spacer block of FIG. 23 coupled to the sensor module and adaptor of FIG. 21 in a rotating orientation and rotated to an opposite maximum rotation position relative to FIG. 24;

FIG. 26 is a bottom plan view of a mobile tibial trial of FIG. 19 having rotation key aperture;

FIG. 27 is a bottom plan view of a fixed tibial trial having a non-rotation key aperture;

FIG. 28 is a simplified block diagram of one embodiment of a computer assisted surgery system of the system of FIG. 1;

FIG. 29 is a simplified flow diagram of one embodiment of a method for performing an orthopaedic surgical procedure using the computer assisted surgery system of FIG. 28;

FIG. 30 is a simplified flow diagram of one embodiment of a method for determining and displaying navigation and joint force data that may be executed by the computer assisted surgery system of FIG. 28;

FIG. 31 is a simplified flow diagram of one embodiment of a method for determining and displaying flexion angle and force data of a patient's joint that may be executed by the computer assisted surgery system of FIG. 28;

FIG. 32 is a simplified flow diagram of one embodiment of a method for performing an orthopaedic surgical procedure using the system of FIG. 1;

FIG. 33 is a perspective view of a patient's joint in extension during an orthopaedic surgical procedure using the sensor module of FIG. 2;

FIG. 34 is a perspective view of a patient's joint during an orthopaedic surgical procedure using the distractor and sensor module of FIG. 1;

FIG. 35 is another perspective view of a patient's joint in flexion during an orthopaedic surgical procedure using the sensor module of FIG. 2;

FIG. 36 is another perspective view of a patient's joint in extension during an orthopaedic surgical procedure using the sensor module of FIG. 2; and

FIG. 37 is another perspective view of a patient's joint in flexion during an orthopaedic surgical procedure using the sensor module of FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior, medial, lateral, superior, inferior, etcetera, may be used throughout this disclosure in reference to both the orthopaedic implants described herein and a patient's natural anatomy. Such terms have well-understood meanings in both the study of anatomy and the field of orthopaedics. Use of such anatomical reference terms in the specification and claims is intended to be consistent with their well-understood meanings unless noted otherwise.

Referring now to FIG. 1, in one embodiment, a system 10 for determining and displaying joint forces of a patient's joint during an orthopaedic surgical procedure includes a sensor module 12 and a hand-held display module 14. In some embodiments, the system 10 may also include a joint distractor 16, which is configured to receive the sensor module 12 as discussed below. Additionally, in some embodiments, the system 10 may include a computer assisted surgery system (CAOS) system 18. As discussed in more detail below, the sensor module 12 is configured to be inserted into a patient's knee joint and provide a visual indication of the medial-lateral balance of the knee joint forces to an orthopaedic surgeon. The sensor module 12 may also be configured to transmit joint force data to the hand-held display module 14 via a wireless communication link 20 and/or the computer assisted surgery system 18 via a wireless communication link 22. In response, the display module 14 and/or computer assisted surgery system 18 are configured to display the joint force data, or data derived therefrom, to an orthopaedic surgeon. Additionally, during the performance of an orthopaedic surgical procedure, such as a total or partial knee arthroplasty procedure, the sensor module 12 may be coupled to the joint distractor 16 to provide visual indication of the joint forces of the patient's joint during distraction thereof.

Referring now to FIGS. 2-11, the sensor module 12 includes a sensor housing 30 and an elongated handle 32 coupled to the sensor housing 30. The sensor housing 30 is sized and shaped to be positioned in a joint of the patient. In the illustrative embodiment, the sensor housing 30 is embodied as a tibial paddle 34, which is shaped to be positioned in a knee joint of the patient. However, the sensor housing 30 may be configured to be used with other joints of the patient in other embodiments.

In use, the tibial paddle 34 is configured to be positioned on a proximal plateau of a patient's resected tibia (see, e.g., FIG. 33-37). As discussed in more detail below, the tibial paddle 34 may be placed in contact with the patient's tibia or may be placed on an intervening platform or other member. Additionally, as discussed in more detail below, the tibial paddle 34 is designed for use with an adaptor 502 (see FIG. 19) and various other orthopaedic surgical instruments, including spacer blocks, balancer/sizer instruments, orthopaedic trials, and/or trial assemblies.

The sensor module 12 may be used on the patient's left or right knee. For example, the sensor module 12 may be used on a patient's left knee via a medial surgical approach wherein the tibial paddle 34 is inserted into the patient's left knee joint via a medial capsular incision. In such position, as discussed below, the handle 32 extends out of the medial capsular incision. Alternatively, by simply flipping or turning over the sensor module 12, the module 12 may be used on the patient's left knee via a lateral surgical approach wherein the tibial paddle 34 is inserted into the patient's left knee joint via a lateral capsular incision. Again, in such position, the handle 32 extends out of the lateral capsular incision.

As such, it should be appreciated that sensor module 12 may be used on the patient's left or right knee using a medial or lateral surgical approach. For clarity of description, the sensor module 12 and the system 10 are described below with reference to an orthopaedic surgical procedure using a medial surgical approach (i.e., using a medial capsular incision to access the patient's joint). However, it should be appreciated that such description is equally applicable to lateral surgical approach procedures. As such, some structures are described using particular anatomical references (e.g., lateral and medial) with the understanding that such references would be flipped or switched when the module 12 is used in a lateral surgical approach procedure. For example, a “medial side” of the tibial paddle 34 becomes a “lateral side” of the tibial paddle 34 when used in a lateral surgical approach procedure.

The tibial paddle 34 is planar or substantially planar and has a shape generally corresponding to the shape of the orthopaedic prosthesis to be implanted in the patient. For example, in the illustrative embodiment, the tibial paddle 34 has a shape generally corresponding to a knee prosthesis of a particular size. However, in other embodiments, the paddle 34 (or sensor housing 30) may have a shape generally corresponding to other types of orthopaedic prostheses such as a hip prosthesis, a shoulder prosthesis, an ankle prosthesis, a spine prosthesis, or a patella prosthesis.

The illustrative tibial paddle 34 includes a curved anterior side 36, a curved lateral side 38, a curved medial side 40, and a curved posterior side 42, each shaped to approximate the shape a tibial bearing of an orthopaedic knee prosthesis. Again, as discussed above, the lateral side 38 and the medial side 40 are lateral and medial sides, respectively, in those embodiments wherein the sensor module 12 is used in a lateral surgical approach procedure. The posterior side 42 includes a posterior notch 43 to allow the tibial paddle 34 to be positioned around the soft tissue of the patient's joint such as the posterior cruciate ligament.

The tibial paddle 34 includes an inner sidewall 44, which defines a vertical aperture or passageway 45 through the tibial paddle 34. The aperture 45 is centrally located on the tibial paddle 34 and, as discussed in more detail below, is shaped and configured to receive an adaptor 502 (see FIG. 19) for attaching various tibial trials and trial assemblies to the sensor module 12. As discussed in more detail below with regard to FIG. 22, the inner sidewall 44 includes an inwardly angled section 47 to facilitate the attachment and removal of the adaptor 502.

The tibial paddle 34 also includes an anterior alignment aperture 46 and a posterior alignment aperture 48. The anterior alignment aperture 46 is located anteriorly (i.e., toward the curved anterior side 36) of the aperture 45, and the posterior alignment aperture 48 is located posteriorly (i.e., toward the posterior notch 43) of the aperture 45. The alignment apertures 46, 48 are inwardly curved in the transverse plane (i.e., a plane defined by the tibial paddle 34) and generally lie along a circle concentric with the aperture 45. Illustratively, the alignment apertures 46, 48 are “keyed” such that the anterior alignment aperture 46 has a greater width (i.e., a medial-to-lateral width) than the posterior alignment aperture 48. As discussed in more detail below, the “keying” of the alignment apertures 46, 48 allow the adaptor 502, or other instruments or devices, to be coupled to the sensor module 12 in a predefined orientation. Of course, it should be appreciated that other features and/or structures may be used in other embodiments to provide a “keyed” coupling to the sensor module 12. For example, in other embodiments, the posterior alignment aperture 48 may have a width greater than the anterior alignment aperture 46, additional or fewer alignment apertures may be used, alignment apertures having different “keyed” shapes may be used, and/or the like.

In some embodiments, the tibial paddle 34 may include an anterior-to-posterior axis indicia 41, such as a printed line, that provides a visual indication of an anterior-to-posterior bisecting axis 59 of the tibial paddle 34. In use, an orthopaedic surgeon or other healthcare provider may use the indicia 41 to help align the tibial paddle 34 within the patient's knee joint. Additionally, in some embodiments, the tibial paddle 34 may include an adaptor indicia 49, such as a printed line, that provides a visual indication of proper positioning of the adaptor 502 when coupled to the tibial paddle 34 of the sensor module 12.

The overall size of the tibial paddle 34 may be selected based on the particular anatomical structure of the patient. For example, in some embodiments, the tibial paddle 34 may be provided in various sizes to accommodate patients of varying sizes. It should be appreciated that the general shape and size of the paddle 34 (and sensor housing 30) is designed and selected such that the paddle 34 or housing 30 does not significantly overhang with respect to the associated bony anatomy of the patient such that the paddle 34 or housing 30 nor adversely impinge the surrounding soft tissue.

The handle 32 includes a pair of displays 50, 52 coupled to a distal end 54 of the handle 32. Another end 56 of the handle 32 opposite the distal end 54 is coupled to the tibial paddle 34. In the illustrative embodiment of FIG. 2, the handle 32 and tibial paddle 34 are substantially monolithic in structure. However, in other embodiments, the tibial paddle 34 may be removably coupled to the handle 32 via a suitable connector or the like.

As illustrated in FIGS. 3 and 4, the elongated handle 32 extends from a side of the tibial paddle 34 and defines a longitudinal axis 57, which is offset from the anterior-to-posterior bisecting axis 59 of the tibial paddle 34 such that an angle 55 greater than 0 degrees is defined between the axes 57, 59. In the illustrative embodiment, the handle 32 extends from the medial side 40 (which is a lateral side when the sensor module 12 is used in a lateral surgical approach procedure). It should be appreciated that because the handle 32 extends from a side of the paddle 34, the tibial paddle 34 may be positioned in a knee joint of a patient without the need to sublux or evert the patient's patella. That is, the tibial paddle 34 may be properly positioned between the patient's proximal tibia and distal femur with the patient's patella in the natural position.

Depending on the particular surgical approach to be used by the orthopaedic surgeon, the surgeon may flip the sensor module 12 to the proper orientation such that the tibial paddle 34 is inserted into the patient's knee joint through the associated capsular incision. In either orientation, the handle 32 extends out of the capsular incision and at least one of the displays 50, 52 is visible to the orthopaedic surgeon. For example, if the orthopaedic surgeon is using a medial surgical approach on a patient's left knee, the orthopaedic surgeon may position the sensor module 12 in the orientation illustrated in FIG. 3 such that the handle 32 extends from the medial side of the patient's knee (through the medial capsular incision) when the tibial paddle 34 is inserted into the knee joint and the display 50 is visible to the surgeon. Alternatively, if the orthopaedic surgeon is using a lateral surgical approach on a patient's left knee, the orthopaedic surgeon may position the sensor module 12 in the orientation illustrated in FIG. 4 such that the handle 32 extends from the lateral side of the patient's knee (through the lateral capsular incision) when the tibial paddle 34 is inserted into the knee joint and the display 52 is visible to the surgeon.

As discussed above, the sensor module 12 is configured to assist a surgeon during the performance of an orthopaedic surgical procedure. As such, the sensor module 12 includes an outer housing 58 formed from a bio-compatible material. For example, the outer housing 58 may be formed from a bio-compatible plastic or polymer. In one particular embodiment, the sensor module 12 is configured for single-usage and, as such, is provided in a sterile form. For example, the sensor module 12 may be provided in a sterile packaging. However, in those embodiments wherein the tibial paddle 34 is removably coupled to the handle 32, the tibial paddle 34 may be designed for single-usage and the handle 32 may be configured to be reusable via an autoclaving procedure or the like.

As illustrated in FIG. 5, the outer housing 58 of the sensor module 12 includes an upper housing 60 and a lower housing 62, which are coupled to each other. In some embodiments, the upper housing 60 and the lower housing 62 are mirror images of each other. The upper housing 60 includes an interior surface 61 that confronts, or otherwise, faces an interior surface 63 of the lower housing 62 when the housings 60, 62 are coupled to each other. Additionally, the upper housing 60 includes an upper tibial paddle housing 64 and an upper handle housing 66. Similarly, the lower housing 62 includes a lower tibial paddle housing 68 and a lower handle housing 70. The upper tibial paddle housing 64 has a planer or substantially planar outer surface 65 and includes an inner sidewall 72 that defines, in part, the vertical aperture 45 extending through the tibial paddle 34. Similarly, the lower tibial paddle housing 68 has a planer or substantially planar outer surface 69 and includes an inner sidewall 74 that defines, in part, the vertical aperture 45.

The display 50 is coupled to the distal end 54 of the upper housing 60 and the display 52 is coupled to the distal end 54 of the lower housing 62. As illustrated in FIG. 6, each of the displays 50, 52 is illustratively embodied as a row or an array of light emitting diodes. However, in other embodiments, the displays 50, 52 may be embodied as other types of displays such as liquid crystal displays, segmented displays, and/or the like. In the illustrative embodiment of FIG. 6, each of the displays 50, 52 includes five separate light emitting diodes 80, 82, 84, 86, 88. As discussed in more detail below, the central light emitting diodes 84 are illuminated when the medial-lateral joint forces of the patient's knee joint are approximately equal. Additionally, the light emitting diodes 80 and/or 82 are illuminated when the medial joint force is greater than the lateral joint force of the patient's knee joint by a predetermined threshold amount and the light emitting diodes 86 and 88 are illuminated when the lateral joint force is greater than the medial joint force of the patient's knee by the predetermine threshold amount (again, assuming a medial surgical approach). As shown in FIG. 6, the light emitting diodes 80, 82, 84, 86, 88 of the displays 50, 52 are arranged such that the light emitting diodes 80, 82 correspond with the medial side 40 of the tibial paddle 34 and the light emitting diodes 86, 88 correspond with the lateral side 38 of the tibial paddle 34 regardless of the orientation (i.e., regardless of whether the upper housing 60 or the lower housing 62 is facing upwardly).

As discussed in more detail below, the light emitting diodes 80,82, 84, 86, 88 may be illuminated in one of a plurality of illumination configurations according to a predetermined display protocol to provide a visual indication to the surgeon of the relative medial-lateral joint force balance. By activating or illuminating one or more of the light emitting diodes 80, 82, 84, 86, 88, an orthopaedic surgeon may visual determine which side of the patient's joint is exerting a greater amount of force and the general magnitude of such force relative to the opposite side of the patient's knee joint. For example, one illustrative display protocol is presented in graph 170 in FIG. 7, which includes nine separate illumination configurations. According to the illustrative display protocol 170, only the light emitting diode 80 is illuminated if the medial force component is between 85%-100% and the lateral force component is between 0%-15%. However, both light emitting diodes 80 and 82 are illuminated if the medial force component is between 75%-84% and the lateral force component is between 16%-25%. If the medial force component is between 65%-74% and the lateral force component is between 26%-35%, only the light emitting diode 82 is illuminated. If the medial force component is between 55%-64% and the lateral force component is between 36%-45%, both light emitting diodes 82 and 84 are illuminated. If the medial force component is between 46%-54% and the lateral force component is between 46%-54%, only the light emitting diode 84 is illuminated, which indicates a relative equal balance of medial and lateral forces. If the medial force component is between 36%-45% and the lateral force component is between 55%-64%, both light emitting diodes 84 and 86 are illuminated. If the medial force component is between 26%-35% and the lateral force component is between 65%-74%, only the light emitting diode 86 is illuminated. If the medial force component is between 26%-35% and the lateral force component is between 75%-84%, both light emitting diodes 86 and 88 are illuminated. And, if the medial force component is between 0%-15% and the lateral force component is between 85%-100%, only the light emitting diode 88 is illuminated. In this way, a visual indication of the relative medial-lateral joint balance of the joint force of the patient's knee is provided to the orthopaedic surgeon. Of course, in other embodiments, other display protocols may be used to control and illuminate the displays 50, 52.

The sensor module 12 includes a sensor array 90 positioned in the tibial paddle 34 and communicatively coupled to a control circuit 92 positioned in the handle 32. The sensor array 90 is “sandwiched” between the upper housing piece 60 and the lower housing piece 62 and includes a centrally-located aperture 91 through which the vertical aperture or passageway 45 extends when the upper housing 60 and a lower housing 62 of the outer housing 58 of the sensor module 12 are coupled together. The anterior alignment aperture 46 and the posterior alignment aperture 48 also extend through the aperture 91 when the upper housing 60 and a lower housing 62 of the outer housing 58 of the sensor module 12 are coupled together. The upper housing piece 60 and the lower housing piece 62 are spaced apart to allow the sensor array 90 to be compressed by the joint force applied to the tibial paddle 34. For example, as illustrated in FIG. 6, the upper housing 64 includes an outer rim 94 and the lower housing 66 includes an outer rim 96, which is spaced apart from the outer rim 94 of the upper housing 64 by a distance 98. When a joint force is applied to the tibial paddle 34, the outer rims 94, 96 are moved toward each as the sensor array 90 is compressed.

The sensor array 90 includes a plurality of pressure sensors or sensor elements 100 configured to generate sensor signals indicative of the joint force applied to the sensor array 90. In the illustrative embodiment, the pressure sensors 100 are embodied as capacitive pressure sensors, but may be embodied as other types of sensors in other embodiments. The pressure sensors 100 of the sensor array 90 may be arranged in a particular configuration. For example, in one embodiment as illustrated in FIG. 8, the sensor array 90 includes a set of medial-anterior sensors 180 configured to measure a medial-anterior component of the joint force, a set of lateral-anterior sensors 182 configured to measure a lateral-anterior component of the joint force, a set of medial-posterior sensors 184 configured to measure a medial-posterior component of the joint force, and a set of lateral-posterior sensors 186 to measure a lateral-posterior component of the joint force. Illustratively, the set of medial-anterior sensors 180 includes an anterior-most sensor 102, a sensor 104 located posteriorly from the anterior-most sensor 102 and toward the center of the sensor array 90, and a sensor 106 located posteriorly from the anterior-most sensor 102 and located toward a medial side 190 of the sensor array 90. The set of lateral-anterior sensors 182 includes an anterior-most sensor 108, a sensor 110 located posteriorly from the anterior-most sensor 108 and toward the center of the sensor array 90, and a sensor 112 located posteriorly from the anterior-most sensor 108 and located toward a lateral side 192 of the sensor array 90. The set of medial-posterior sensors 184 includes a posterior-most sensor 114, a sensor 116 located anteriorly from the posterior-most sensor 114 and toward the center of the sensor array 90, and a sensor 118 located anteriorly from the posterior-most sensor 114 and located toward the medial side 190 of the sensor array 90. The set of lateral-posterior sensors 186 includes a posterior-most sensor 120, a sensor 122 located anteriorly from the posterior-most sensor 120 and toward the center of the sensor array 90, and a sensor 124 located anteriorly from the posterior-most sensor 120 and located toward the lateral side 192 of the sensor array 90.

The sets of medial-anterior sensors 180 and lateral-anterior sensors 182 form a set of anterior sensors 194, and the sets of medial-posterior sensors 184 and lateral-posterior sensors 186 form a set of posterior sensors 195. Similarly, the sets of medial-anterior sensors 180 and medial-posterior sensors 184 form a set of medial sensors 196, and the sets of lateral-anterior sensors 182 and lateral-posterior sensors 186 form a set of lateral sensors 197. In the illustrative embodiment of FIG. 8, each of the medial-anterior sensors 180 has a surface area equal, or substantially equal, to the surface area of each of the lateral-anterior sensors 182. Similarly, each of the medial-posterior sensors 184 has a surface area equal, or substantially equal, to the surface area of the lateral-posterior sensors 186. Additionally, in some embodiments, each of the anterior sensors 194 has a surface area less than each of the posterior sensors 195. For example, in one particular embodiment, each of the anterior sensors 194 has a surface area equal to about 0.174 in², and each of the posterior sensors 195 has a surface area equal to about 0.187 in². Additionally, in another particular embodiment, each of the anterior sensors 194 has a surface area equal to about 0.243 in², and each of the posterior sensors 195 has a surface area equal to about 0.263 in². Of course, in other embodiments, the sensor array 90 may include additional or fewer sensors or sensing elements having similar or dissimilar sizes, locations, and/or orientations.

Referring now to FIG. 9, the control circuit 92 includes a processor 130 and a memory device 132. The processor 130 may be embodied as any type of processor configured to perform the functions described herein. For example, the processor 130 may be embodied as a separate integrated circuit or as a collection of electronic devices. Additionally, the processor may be a single or multi-core processor. Although only a single processor 130 is illustrated in FIG. 10, it should be appreciated that in other embodiments, the control circuit 92 may include any number of additional processors. The memory device 132 may be embodied as one or more read-only memory devices and/or random access memory devices. For example, the memory device 132 may be embodied as or otherwise include electrically erasable programmable read-only memory devices (EEPROM), dynamic random access memory devices (DRAM), synchronous dynamic random access memory devices (SDRAM), double-data rate dynamic random access memory devices (DDR SDRAM), and/or other volatile or non-volatile memory devices. Additionally, although only a single memory device is illustrated in FIG. 9, in other embodiments, the control circuit 92 may include additional memory devices.

The processor 130 is communicatively coupled to the memory device 132 via signal paths 134. The signal paths 134 may be embodied as any type of signal paths capable of facilitating communication between the processor 130 and the memory device 132. For example, the signal paths 134 may be embodied as any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. The processor 130 is also communicatively coupled to the sensor array 90 via signal paths 136. Similar to signal paths 134, the signal paths 136 may be embodied as any type of signal paths capable of facilitating communication between the processor 130 and the sensor array 90 including, for example any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. Additionally, the signal path 136 may include a connector 138 (see FIG. 5) configured to receive a plug-end 140 of the sensor array 90.

The control circuit 92 also includes a power source 142 and associated power control circuitry 144. The power source 142 may be embodied as a number of batteries sized to fit in the sensor module 12. The power source 142 is electrically coupled to the power control circuitry 144 via signal paths 146 and the power control circuitry 144 is electrically coupled to the processor 130 and other devices of the control circuit 92 via signal paths 148. The signal paths 146, 148 may be embodied as any type of signal paths including, for example any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. The power circuitry 144 may include power control, distribution, and filtering circuitry and is configured to provide or distribute power from the power source 142 to the processor 130 and other devices or components of the control circuit 92. As discussed in more detail below, the power circuitry 144 may be configured to continuously supply power to the processor 130 and other components of the control circuit 92 after being turned “on” and until the power source 142 is depleted. That is, a user is unable to turn “off” the sensor module 12 after initially turning the module 12 “on” in some embodiments. Such functionality ensures, for example, that the sensor module 12 is not reused in subsequent surgeries.

The control circuit 92 also includes user controls 150 communicatively coupled to the processor 130 via signal paths 152. The user controls 150 are embodied as power buttons 154 (see FIG. 6) located on the displays 50, 52 and selectable by a user to turn the sensor module 12 on. However, in the illustrative embodiment, the control circuit 92 is configured to prevent or otherwise limit the ability of the user from turning off the sensor module 12 via the power buttons 154 or other controls after the sensor module 12 has been turned on. That is, once turned on, the control circuit 92 is configured to remain on until the power source 142 is depleted. Such a configuration ensures that the sensor module 12 is used during a single orthopaedic surgical procedure and is not otherwise reusable in multiple procedures.

The signal paths 152 are similar to the signal paths 134 and may be embodied as any type of signal paths capable of facilitating communication between the user controls 150 and the processor 130 including, for example any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like.

The control circuit 92 also includes display circuitry 156 for driving and/or controlling the displays 50, 52. The display circuitry 156 is communicatively coupled to the processor 130 via signal paths 158 and to the displays 50, 52 via signal paths 160. Similar to the signal paths 134 discussed above, the signal paths 158, 160 may be embodied as any type of signal paths capable of facilitating communication between the processor 130 and display circuitry 156 and the display circuit 156 and displays 50, 52, respectively. For example, the signal paths 158, 160 may be embodied as any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. As discussed above, in the illustrative embodiment, the displays 50, 52 are embodied as an arrangement of light emitting diodes 80, 82, 84, 86, 88.

In some embodiments, the sensor module 12 is configured to transmit force data to the display module 14 and/or computer assisted orthopaedic surgery (CAOS) system 18. In such embodiments, the control circuit 92 includes transmitter circuitry 162 and an antenna 164. The transmitter circuitry 162 is communicatively coupled to the processor 130 via signal paths 166 and to the antenna 164 via signal paths 168. The signal paths 166, 168 may be embodied as any type of signal paths capable of facilitating communication between the transmitter circuitry 162 and the processor 130 and antenna 164, respectively. For example, similar to the signal paths 134, the signal paths 166, 168 may be embodied as any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. The transmitter circuitry 162 may be configured to use any type of wireless communication protocol, standard, or technologies to transmit the joint force data to the display module 14 and/or computer assisted orthopaedic surgery (CAOS) system 18. For example, the transmitter circuitry 162 may be configured to use a wireless networking protocol, a cellular communication protocol such as a code division multiple access (CDMA) protocol, a Bluetooth® protocol, or other wireless communication protocol, standard, or technology.

Referring now to FIGS. 10 and 11, in use, the control circuit 92 is configured to execute a method 200 for determining joint force data of a patient's joint and providing a visual indication of the medial-lateral balance of the joint force of the patient's knee joint. The method 200 begins with block 202 in which the control circuit 92 is initialized. For example, in block 202, the control circuit 92 may perform any number of system checks, clear any registers of the processor 130, and/or perform other initialization and/or integrity checks. Additionally, in some embodiments, the control circuit 92 is configured to perform a handshaking routine in block 204 with the hand-held display device 14 and/or the computer assisted orthopaedic surgery (CAOS) system 18. During the handshaking routine, the control circuit 92 and the hand-held display device 14 and/or the computer assisted orthopaedic surgery (CAOS) system 18 may be configured to determine communication protocols and/or otherwise establish any type of communication procedures for transmitting the joint force data from the sensor module 12 to the device 14 or system 18.

In block 206, the control circuit 92 receives the sensor signals or data from the sensor array 90. As discussed above, the sensor array 90 generates sensor signals indicative of a joint force applied to the tibial paddle 34 when the paddle 34 is positioned in the knee joint of a patient. In block 208, the processor 130 of the control circuit 92 determines joint force data based on the sensor signals received from the sensor array 90. The joint force data is indicative of the joint force of the patient's knee joint. In some embodiments, the joint force data may be embodied as specific joint force values such as a medial joint force component value, a lateral joint force component value, an anterior joint force component value, and/or a posterior joint force component value, each force being determined in Newtons or similar force measurement unit. In such embodiments, the medial joint force component may be determined based on the sensor signals from the set of medial sensors 196, and the lateral joint force component may be determined based on the sensor signals from the set of lateral sensors 197. Additionally, the anterior joint force component may be based on the set of anterior sensors 194, and the posterior joint force component may be based on the sensor signals from the set of posterior sensors 195. Subsequently, in block 210 the control circuit 92 controls or otherwise activates the displays 50, 52 to display the joint force data determined in block 208. For example, in embodiments wherein one or more specific joint forces are determined, the processor 130 may display the determine joint forces or indicia thereof on the displays 50, 52.

Additionally or alternatively, the control circuit 92 may be configured to determine the medial-lateral balance of the joint force and display indicia of such medial-lateral balance on the displays 50, 52 in blocks 208, 210. For example, as illustrated in FIG. 11, the control circuit 92 may execute a method 220 for determining the medial-lateral balance of the joint force of the patient's knee joint. In block 222, the control circuit 92 determines medial joint force data based on the sensor signals received from the set of medial sensors 196. Similarly, in block 224, the control circuit 92 determines lateral joint force data based on the sensor signals received from set of lateral sensors 197. The medial and lateral joint force data may be embodied as the specific joint force determined in Newtons or may be embodied as some representation thereof. For example, in some embodiments, the medial and lateral joint force data is measured in capacitance. Additionally, it should be appreciated that the blocks 222 and 224 may be executed in either order.

In block 226, the control circuit 92 determines the relative medial-lateral balance of the joint force of the patient's joint. To do so, the control circuit 92 compares the medial force data and the lateral force data. For example, in one embodiment, the control circuit 92 is configured to determine a total force value by summing the medial force data and the lateral force data. The control circuit 92 subsequently determines a medial percentage value by dividing the medial force data by the total force value and a lateral percentage value by dividing the lateral force data by the total force value. As such, if the medial and lateral forces of a patient's joint are balanced, the medial percentage value would be determined to be about 50% and the lateral percentage value would be determined to be about 50%. Of course, in some embodiments, the control circuit 92 may be configured to determine only one of the medial and lateral percentage values, the remaining one being known or determined by simple subtraction from 100%.

In block 228, the control circuit 92 activates or controls the displays 50, 52 to provide a visual indication of the relative medial-lateral balance of the joint forces of the patient's joint. For example, in embodiments wherein the displays 50, 52 are embodied as light emitting diodes, the control circuit 92 is configured to activate or illuminate one or more of the light emitting diodes to provide a visual indication of the medial-lateral balance of joint forces. The control circuit 92 may use any display protocol or illumination configuration of the light emitting diodes that provides an appropriate indication to the orthopaedic surgeon of such joint forces. For example, in one particular embodiment, the control circuit 92 is configured to control the displays 50, 52 according to the display protocol 170 illustrated in and discussed above in regard to FIG. 7.

In this way, sensor module 12 provides a visual indication to the orthopaedic surgeon of the relative medial and lateral forces of the patient's joint. As discussed in more detail below, the orthopaedic surgeon can perform balancing procedures on the patient's knee joint while monitoring the current balance of the medial and lateral forces via the displays 50, 52 to achieve the desired balance for the particular patient. Additionally, because the sensor module 12 includes a display 50, 52 on either side, the orthopaedic surgeon is provide the visual indication of the joint forces whether the surgeon is operating on the patient's left or right knee.

Referring back to FIG. 12, in addition to activating the displays 50, 52 to provide the visual notification of the joint forces in block 210, the sensor module 12 may be configured to transmit the joint force data in block 212. As discussed above, the sensor module 12 may transmit the joint force data to the hand-held display 14 and/or computer assisted orthopaedic surgery (CAOS) system 18 in block 212. The transmitted joint force data may be embodied as the specific joint forces measured in Newtons, for example, or may be representations thereof. For example, the sensor signals received from the sensor array 90 or electrical representations of the levels of such signals may be transmitted in block 212. Alternatively, the sensor module 12 may transmit joint force data indicative of the determined medial-lateral balance of the joint force of the patient's joint.

Referring now to FIGS. 12-18, the hand-held display module 14 includes a housing 300 sized to be held in the hands of an orthopaedic surgeon and used during the performance of an orthopaedic surgical procedure. In this way, the display module 14 is configured to be mobile. The display module 14 also includes a display 302 coupled to an upper side 304 of the housing 300. A plurality of user input buttons 306, 308, 310 are also positioned on the upper side 304 of the housing 300 below the display 302. The display module 14 also includes a power button 312. In the illustrative embodiment of FIGS. 20-26, the power button 312 is positioned below the row of input buttons 306, 308, 310, but the buttons 306, 308, 310, 312 may be positioned in other configurations and/or orientations in other embodiments.

As discussed above, the hand-held display module 14 is configured to be used with the sensor module 12 to receive joint force data form the module 12 and display indicia on the display 302 indicative of the joint forces of the patient's joint. Similar to the sensor module 12, the display module 14 may be configured to determine the relative medial-lateral balance of the joint force of the patient's joint and display indicia of such balances on the display 302. Additionally, the display module 14 may be configured to determine the anterior-posterior balance of the joint force of the patient's joint and display indicia of such balances on the display 302. Additionally, the display module 14 may also be configured to perform other functions such as store screenshots and data of the patient's joint forces as displayed on the display 302 and download such data to other devices.

As illustrated in FIG. 14, the hand-held display module 14 includes a control circuit 320 positioned in the housing 300. The control circuit 320 includes a processor 322 and a memory device 324. The processor 322 may be embodied as any type of processor configurable to perform the functions described herein. For example, the processor 322 may be embodied as a separate integrated circuit or as a collection of electronic devices. Additionally, the processor may be a single or multi-core processors. Although only a single processor 322 is illustrated in FIG. 14, it should be appreciated that in other embodiments, the control circuit 320 may include any number of additional processors. The memory device 324 may be embodied read-only memory devices and/or random access memory devices. For example, the memory device 324 may be embodied as or otherwise include electrically erasable programmable memory devices (EEPROM), dynamic random access memory devices (DRAM), synchronous dynamic random access memory devices (SDRAM), double-data rate dynamic random access memory devices (DDR SDRAM), and/or other volatile or non-volatile memory devices. Additionally, although only a single memory device is illustrated in FIG. 14, in other embodiments, the control circuit 320 may include additional memory devices.

The processor 322 is communicatively coupled to the memory device 324 via signal paths 326. The signal paths 326 may be embodied as any type of signal paths capable of facilitating communication between the processor 322 and the memory device 324. For example, the signal paths 326 may be embodied as any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like.

The processor 322 is also communicatively coupled to the user input buttons 306, 308, 310 via signal paths 328 and to a power indicator 314 via signal paths 344. Similar to signal paths 326, the signal paths 328, 344 may be embodied as any type of signal paths capable of facilitating communication between the processor 322 and the user input buttons 306, 308, 310 and the power indicator 314, respectively. For example, the signal paths 328, 344 may include any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. The user input buttons 306, 308, 310 are software or “soft” buttons, the functionality of each of which may be determined based on the particular screen displayed on the display 302.

The control circuit 320 also includes an external power input circuitry 330, a rechargeable power source 332 such as a rechargeable battery or the like, and power circuitry 334. The external power input circuitry 330 is configured to receive a plug of a charger such as a “wall charger” and is communicatively coupled to the rechargeable power source 332 via signal paths 336. The rechargeable power source 332 is communicatively coupled to the power circuitry 334 via signal paths 338. The power circuitry 334 is communicatively coupled to the processor 332 via signal paths 340 and to the power button 312 via signal paths 342. The signal paths 336, 338, 340, 342 may be embodied as any type of signal paths including, for example any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. The power circuitry 334 may include power control, distribution, and filtering circuitry and is configured to provide or distribute power the rechargeable power source 332 to the processor 322 and other devices or components of the control circuit 320.

The control circuit 320 also includes display circuitry 346 for driving and/or controlling the display 392. The display circuitry 346 is communicatively coupled to the processor 322 via signal paths 348 and to the display 302 via signal paths 350. The signal paths 348, 350 may be embodied as any type of signal paths capable of facilitating communication between the processor 322 and display circuitry 346 and the display circuit 346 and display 302, respectively. For example, the signal paths 348, 350 may be embodied as any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like.

As discussed above, the hand-held display module 14 is configured to receive joint force data from the sensor module 12. As such the control circuit 320 includes receiver circuitry 352 and an antenna 354. The receiver circuitry 352 is communicatively coupled to the processor 322 via signal paths 356 and to the antenna 354 via signal paths 358. The signal paths 356, 358 may be embodied as any type of signal paths capable of facilitating communication between the receiver circuitry 352 and the processor 322 and the antenna 354, respectively. For example, the signal paths 356, 358 may be embodied as any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. The receiver circuitry 352 may be configured to use any type of wireless communication protocol, standard, or technologies to receive the joint force data from the sensor module 12. For example, as discussed above in regard to the sensor module 12, the display module 14 may be configured to a wireless networking protocol, a cellular communication protocol such as a code division multiple access (CDMA) protocol, a Bluetooth® protocol, or other wireless communication protocol, standard, or technology to communicate with the sensor module 12.

The control circuit 320 also includes a universal serial bus (USB) interface 360. The USB interface 360 is communicatively coupled to the processor 322 via signal paths 362, which may be embodied as any type of signal paths capable of facilitating communication between the USB interface 360 and the processor 322. For example, the signal paths 362 may be embodied as any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like. The USB interface 360 may be used to download data, such as joint force data or screenshot data, from the display module 14 to another device such as a computer. Additionally, the USB interface 360 may be used to update the software or firmware of the control circuit 320.

Referring now to FIGS. 23-26, in use, the control circuit 320 is configured to execute a method 400 for determining and displaying joint force data related to a patient's joint to an orthopaedic surgeon. The method 400 begins with block 402 in which the control circuit 320 is initialized. For example, in block 402, the control circuit 320 may perform any number of system checks, clear any registers of the processor 322, and/or perform other initialization and/or integrity checks. Additionally, in some embodiments, the control circuit 320 is configured to perform a handshaking routine in block 404 with the sensor module 12. During this handshaking routine, the control circuit 320 and the sensor module 12 may be configured to determine communication protocols and/or otherwise establish any type of communication procedures for transmitting the joint force data from the sensor module 12 to the device module 14.

In block 406, the control circuit 320 receives the joint force data from the sensor module 12. As discussed above, the joint force data is indicative of the joint force of the patient's knee as indicated by the sensor signals generated by the sensor array 90 of the sensor module 12. In block 408, the control circuit 320 determines a medial joint force value and a lateral joint force value based on the joint force data received in block 406. The medial joint force value is based on the set of medial sensors 196 and the lateral joint force value is based on the set of lateral sensors 197. In block 410, the control circuit 320 determines the medial/lateral balance of the joint force of the patient's joint based on the medial and lateral joint force values. As discussed above, the medial/lateral balance may be represented by a percentage value. The medial/lateral balance of the joint force is subsequently displayed on the display 302 in block 412. For example, as illustrated in the screenshots 450, 452, 454 in FIGS. 24, 25, and 26, the medial joint force component percentage value 430 is displayed toward a medially designated side 460 of the display 302 and the lateral joint force component percentage value 432 is displayed toward a laterally designated side 462 of the display 302.

In blocks 414, 416, the control circuit 320 determines which mode the orthopaedic surgeon has selected. In the illustrative embodiment, the orthopaedic surgeon may select a first mode in which indicia of only the medial-lateral balance of the patient's joint forces is displayed on the display 302 or a second mode in which may indicia of the medial-lateral and the anterior-posterior balance of the patient's joint forces is displayed in the display 302. The user may switch between the two modes by selecting the appropriate user input buttons 306, 308, 310.

If the orthopaedic surgeon has selected the medial-lateral only mode, the method 400 advances to block 418 in which indicia of the medial-lateral balance of the joint force of the patient's knee joint are displayed on the display 302. To do so, as illustrated in FIG. 16, a screen display 450 is presented on the display 302 of the display module 14. The screen display 450 includes a background image 470, which is illustratively embodied as an image of a proximal end of a resected tibia. The control circuit 320 displays a balance bar 472 on the background image 470 and an icon 474 on the balance bar 472 in a position that indicates the relative medial-lateral balance of the joint forces of the patient's joint. For example, in the illustrative screen display 450, the icon 474, which is embodied as a rounded rectangle, is displayed on the balance bar 472 toward the lateral side 462 of the screen display 450 (i.e., the side of the display 302 corresponding to the lateral side of the resected tibia image 470, which illustrative corresponds to the right side of the display 302). Such positioning indicates that the lateral force component of the total joint force of the patient's knee joint is greater than the medial joint force component. The farther way the icon 474 is located from the center of the balance bar 472, the greater the respective medial or lateral force component. In some embodiments, the background image 470 includes a “balanced” icon 476, illustratively embodied as a rounded rectangular outline, positioned on the background image 470 such that when the icon 474 is located within the boundaries of the icon 476, the medial joint force and the lateral joint force of the patient's knee are balanced or within a predetermined threshold of each other. Additionally, in some embodiments, the screen display 450 may include a total force fill bar 434, which may be filled or unfilled as the total force balance is increased or decreased depending on the particular configuration of the display 450.

If, however, the orthopaedic surgeon has selected the medial-lateral and anterior-posterior mode, the method 400 advances to block 420 in which indicia of the medial-lateral and anterior-posterior balance of the joint force of the patient's knee are displayed on the display 302. To do so, as illustrated in FIG. 17, a screen display 452 is presented on the display 302 of the display module 14. The screen display 450 includes the background image 470 on which the balance bar 472 is overlaid. Again, the control circuit 320 displays the icon 474 in a on the balance bar 472 indicative of the relative medial-lateral balance of the joint force of the patient's joint. In addition, however, a medial end 480 of the balance bar 472 and a lateral end 482 of the balance bar 472 are positioned based on the corresponding anterior-posterior balance. For example, the medial end 480 of the balance bar 472 is positioned toward the posterior side 464 of the display 302 or the anterior side 466 of the display 302 based on the anterior-posterior balance of the medial joint force. As discussed above, the anterior-posterior balance of the medial joint force component may be determined based on the sensor signals from the set of medial-anterior sensors 180 and the set of medial-posterior sensors 184. Similarly, the lateral end 482 of the balance bar 472 is positioned toward the posterior side 464 of the display 302 or the anterior side 466 of the display 302 based on the anterior-posterior balance of the lateral joint force. As discussed above, the anterior-posterior balance of the lateral joint force component may be determined based on the sensor signals from set of lateral-anterior sensors 182 and the set of lateral-posterior sensors 186.

In the illustrative screen display 452 of FIG. 18, the medial end 480 of the balance bar 472 is positioned toward the anterior side 466 of the display 302 and the lateral end 482 of the balance bar 472 is positioned toward the posterior side 464 of the display 302. Such positioning indicates that the anterior force component of the medial force component is greater than the posterior force component of the medial force component and that the posterior force component of the lateral force component is greater than the anterior force component of the lateral force component. The farther way the ends 480, 482 are from the anterior-posterior center, the greater the respective anterior or posterior force component.

Referring now back to FIG. 15, once the appropriate indicia of the joint force balances have been displayed on the display 302, the control circuit 320 determines whether the orthopaedic surgeon would like to take a snapshot of the current display in block 422. The orthopaedic surgeon may take a screenshot of the display 302 by selecting the appropriate user input button 306, 308, 310. Additionally, the screenshot is stored in the memory device 324 in block 424 and may be subsequently downloaded from the display module 14.

When a screenshot is stored, an icon 484 appears in the lower right corner of the display 302. In addition to the icon 484, in some embodiments, a corresponding vertical balance line 486 is displayed on the display 302 when a screenshot is stored. The balance line 486 provides a visual indication of the medial-lateral balance of the joint force displayed in the associated stored screenshot. Further, if the orthopaedic surgeon has selected the medial-lateral and anterior-posterior mode, an anterior-posterior balance line 488 is displayed on the display 302. The balance line 488 provides a visual indication of the anterior-posterior balance of the medial and lateral forces of the patient's knee joint displayed in the associated stored screenshot.

Referring now to FIGS. 19-27, in some embodiments, the sensor module 12 may be used with a tibial trialing system 500. The tibial trialing system 500 includes an adaptor 502 and one or more tibial trialing components configured be positioned over the adaptor 502 on the tibial paddle 34 as discussed in more detail below. In the illustrative embodiment, the tibial trialing components of the system 500 may include, for example, one or more trialing shims 504, tibial bearing surface trials 505 that may be coupled to the trialing shims 504, and/or one more tibial bearing trials 506. In some embodiments, the tibial bearing trials 506 may be configured to receive the adaptor 502 as discussed below with regard to FIGS. 26 and 27, while the tibial bearing surface trials 505 may be configured to couple to a selected trialing shim 504. For example, tibial bearing surface trial 505 may include a pair of lugs or protrusions (not shown) shaped and located to be received in a pair of corresponding apertures 508 of the trialing shim 504 to couple the tibial bearing trial surface trial 505 to the trialing shim 504, thereby forming a modular tibial bearing trial.

As discussed above, the adaptor 502 is configured to couple or otherwise connect to the tibial paddle 34 of the sensor module 12. As shown in FIGS. 20A-20E, the adaptor 502 includes a hub 510 having a bottom side 512, which contacts or otherwise confronts the tibial paddle 34 when the adaptor 502 is couple thereto, and a top side 514 opposite the bottom side 512. Illustratively, the hub 510 has a circular shape, or near-circular shape. However, in other embodiments, the hub 510 may be formed to have other geometric shapes capable of facilitating rotation of attached rotatable tibial trialing components as discussed in more detail below. Additionally, the illustrative adaptor 502 is formed from a plastic material, but may be formed from other materials having enough flexibility to allow the clip to be coupled to the tibial paddle 34 and any tibial trialing component while retaining such coupling during use.

A set of upper retainer clips 516 extend upwardly from the top side 514. Each upper retainer clip 516 includes an elongated stem 518 attached to the hub 510 and a lip or nub 520 attached to a distal end of the elongated stem 518. The elongated stem 518 extends upwardly from the hub 510, and the associated lip 520 extends outwardly from the distal end of the elongated stem 518. Each of the upper retainer clips 516 is inwardly curved in the transverse plane (i.e., the plane of the tibial paddle 34 when the adaptor 502 is coupled thereto) and is arranged to generally define a circle. Additionally, each lip or nub 520 has a curved or rounded exterior surface. As discussed in more detail below, the upper retainer clips 516 are shaped and configured to facilitate attachment and detachment of a spacer block 832 and/or the joint distractor 16 during a surgical procedure. Although the illustrative adaptor 502 includes three upper retainer clips 516, additional or fewer upper retainer clips 516 may be used in other embodiments.

Similar to the upper retainer clips 516, a set of lower retainer clips 522 extend downwardly from the bottom side 512. Each lower retainer clip 522 includes an elongated stem 524 attached to the hub 510 and a lip or nub 526 attached to a distal end of the elongated stem 524. The elongated stem 524 extends downwardly from the hub 510, and the associated lip 526 extends outwardly from the distal end of the elongated stem 524. Each of the lower retainer clips 522 is inwardly curved in the transverse plane (i.e., the plane of the tibial paddle 34 when the adaptor 502 is coupled thereto) and is arranged to generally define a circle. Additionally, each lip or nub 526 has a number of substantially planar exterior surfaces that intersect at selected angles. It should be appreciated that in other embodiments the nub 526 may include curved or rounded exterior surfaces. As discussed in more detail below, the lower retainer clips 522 are shaped and configured to facilitate attachment and detachment of the adaptor 502 to the tibial paddle 34 of the sensor module 12. To do so, the lower retainer clips 522 are received in the vertical aperture 45 of the tibial paddle 34. Although the illustrative adaptor 502 includes three lower retainer clips 522, additional or fewer lower retainer clips 522 may be used in other embodiments.

The upper retainer clips 516 and the lower retainer clips 522 are “keyed” such that the adaptor 502 is couplable to the tibial paddle 34 in a single vertical orientation. In the illustrative embodiment, the upper retainer clips 516 are larger than the lower retainer clips 522 such that the upper retainer clips 516 cannot be inserted into the vertical aperture 45 of the tibial paddle 34. For example, the upper retainer clips 516 generally define circle 550 (see FIG. 20E) having a diameter greater than a circle 552 generally defined by the lower retainer clips 522 (see FIG. 20D). Of course, other structures or features may be used in other embodiments to “key” the adaptor 502 to the tibial paddle 34.

As shown in FIG. 20B, the adaptor 502 also includes an anterior alignment tab 530 and a posterior alignment tab 532, which extend downwardly from the bottom side 514. As discussed in more detail below, the alignment tabs 530, 532 are configured to be received in the corresponding alignment apertures 46, 48 of the tibial paddle (see FIG. 19) when the adaptor 502 is coupled to the tibial paddle 34. The alignment tabs 530, 532 are “keyed” such that the adaptor 502 is attachable to the tibial paddle 34 in a single orientation. For example, in the illustrative embodiment, the anterior alignment tab 530 has a greater width or arc length 534 than the width or arc length 536 of the posterior tab 532 (see FIG. 20D). Similarly, as discussed above, the anterior alignment aperture 46 of the tibial paddle 34 has a greater width or arc length than the posterior alignment aperture 48. As such, the adaptor 502 is attachable to the tibial paddle 34 only in the orientation in which the anterior alignment tab 530 is received in the anterior alignment aperture 46 and the posterior alignment tab 532 is received in the posterior alignment aperture 48. Each of the alignment tabs 530, 532 are inwardly curved in the transverse plane and include angled sides 538, 540, respectively, which facilitate the auto-detachment of the adaptor 502 from the tibial paddle 34 in response to excessive torque being exerted on the adaptor 502 as discussed in more detail below.

The adaptor 502 also includes an anti-rotation key or protrusion 542, which extends outwardly from the hub 510. The anti-rotation key 542 includes a bottom surface 544 that is co-planer with the bottom side 512 of the hub 510 such that the anti-rotation key 542 rests on, contacts, or otherwise confronts the tibial paddle 34 when the adaptor 502 is coupled to the sensor module 12. In the illustrative embodiment, the anti-rotation key 542 has a rectangular shape, but may have other shapes in other embodiments. As discussed in more detail below, the anti-rotation key 542 prevents or restricts rotation of non-mobile tibial trial components and limits the rotation of mobile tibial trial components.

As discussed above, the adaptor 502 is configured to be attached to the tibial paddle 34 of the sensor module 12 as shown in FIG. 21. To do so, the lower retainer clips 522 are inserted into the vertical aperture 45 of the tibial paddle 34, and the adaptor 502 is aligned such that the anterior alignment tab 530 is received in the anterior alignment aperture 46 and the posterior alignment tab 532 is received in the posterior alignment aperture 48 of the tibial paddle 34 as shown in FIG. 22. The lower retainer clips 522 are configured to flex inwardly slightly to allow attachment of the adaptor 502 to the tibial paddle 34. Upon successful insertion, the lower retainer clips 522 return to their normal, or near normal, position to provide an amount of lift-off resistance to thereby secure the adaptor 502 to the tibial paddle 34. As shown in FIG. 22, the lip or nub 526 contact the inwardly angled section 47 of the inner sidewall 44 of the tibial paddle 34, which provides an amount of lift-off resistance for the adaptor 502. However, if excessive torque is applied to the adaptor 502, the inwardly angled section 47 of the inner sidewall 44 of the tibial paddle 34 facilitates the detachment of the adaptor 502 by forcing the lower retainer clips 522 inwardly as discussed in more detail below.

As shown in FIGS. 23-25, the trialing shim 504 may be coupled to the adaptor 502 and sensor module 12 in a fixed (FIG. 23) or mobile (FIGS. 24 and 25) orientation. To facilitate such orientations, the trialing shim 504 includes a central aperture 560 sized and shaped to receive the hub 510 of the adaptor 502. Additionally, the trialing shim 504 includes a anti-rotation aperture 562 and a rotation-enabling aperture 564, each in fluid communication with the central aperture 560. As shown in FIG. 23, anti-rotation aperture 562 has a width 566 slightly larger than the anti-rotation key 542 of the adaptor 502 such that the anti-rotation key 542 is receivable in the anti-rotation aperture 562. Conversely, the rotation-enabling aperture 564 has a generally trapezoidal shape and an length 568 that is substantially greater than the width of the anti-rotation key 542.

As shown in FIG. 23, the trialing shim 504 may be coupled to the adaptor 502 and the sensor module 12 in a fixed orientation such that the anti-rotation key 542 of the adaptor 502 is received in the anti-rotation aperture 562 of the trialing shim 504. Because the anti-rotation aperture 562 is only slightly larger than the anti-rotation key 542, substantial rotation of the trialing shim 504 relative to the tibial paddle 34 is restricted or otherwise prevented. Alternatively, as shown in FIGS. 34 and 35, the trialing shim 504 may be coupled to the adaptor 502 and the sensor module 12 in a mobile orientation such that the anti-rotation key 542 of the adaptor 502 is received in the rotation-enabling aperture 564 of the trialing shim 504. Because the rotation-enabling aperture 564 is significantly larger than the anti-rotation key 542, rotation of the trialing shim 504 relative to the tibial paddle 34 is facilitated or otherwise allowed.

In either the fixed or mobile orientation, the application of an excessive torque to the adaptor 502 causes the adaptor 502 to detach from the tibial paddle 34. That is, as the excessive torque is applied to the adaptor 502, the angled sides 538, 540 of the alignment tabs 530, 532 engage the corresponding angled sides of the alignment apertures 46, 48, which generates a lift-off force. The lift-off force, in turn, causes the lower retainer clips 522 to be pushed inwardly via the inwardly angled section 47 of the inner sidewall 44 of the tibial paddle 34. As such, the adaptor 502 is auto-detached from the tibial paddle 34. In this way, damage to the adaptor 502 and sensor module 12 may be avoided.

As discussed above, the tibial bearing trial 506 may be configured to couple to the adaptor 502. The tibial bearing trial 506 may be embodied as a fixed or mobile bearing trial. For example, as shown in FIG. 26, a mobile tibial bearing trial 570 includes a central aperture 572 sized and shaped to receive the hub 510 of the adaptor 502 and a rotation-enabling aperture 574 in fluid communication with the central aperture 572. Similar to the rotation-enabling aperture 564 of the trialing shim 504, the rotation-enabling aperture 574 has a generally trapezoidal shape and an arc length 576 that is substantially greater than the width of the anti-rotation key 542. As such, when the mobile tibial bearing trial 570 is coupled to the adaptor 502 and sensor module 512, rotation of the mobile tibial bearing trial 570 relative to the tibial paddle 34 of the sensor module 512 is facilitated or otherwise allowed.

Alternatively, the tibial bearing trial 506 may be embodied as a fixed tibial bearing trial 580 as shown in FIG. 27. The fixed tibial bearing trial 580 includes a central aperture 582 sized and shaped to receive the hub 510 of the adaptor 502 and an anti-rotation aperture 584 in fluid communication with the central aperture 582. Similar to the anti-rotation aperture 562 of the trialing shim 504, the anti-rotation aperture 584 has a width slightly greater than the width of the anti-rotation key 542 of the adaptor 502 such that the anti-rotation key 542 is receivable in the anti-rotation aperture 562. As such, when the fixed tibial bearing trial 580 is coupled to the adaptor 502 and sensor module 512, rotation of the fixed tibial bearing trial 580 relative to the tibial paddle 34 of the sensor module 512 is restricted or otherwise prevented.

Referring now to FIGS. 28-31, in some embodiments, the sensor module 12 may be configured for use with the computer assisted orthopaedic surgery (CAOS) system 18. In such embodiments, the sensor module 12 is configured to transmit the joint force data to the system 18. As illustrated in FIG. 28, the computer assisted orthopaedic surgery (CAOS) system 18 includes a computer 600, a display 602, and a camera unit 604. The computer 600 is communicatively coupled to the display 602 via signal paths 606 and to the camera unit 604 via signal paths 608. The signal paths 606, 608 may be embodied as any type of signal paths capable of facilitating electrical communication between the computer 600 and the display 602 and the computer 600 and the camera unit 604, respectively. For example, the signal paths may be embodied as any number of wires, printed circuit board traces, via, bus, intervening devices, and/or the like.

The display 602 may be embodied as any type of device such as a liquid crystal display monitor, a cathode ray tube (CRT) display monitor, or the like. Additionally, in some embodiments, the display 602 may be embodied as a “heads-up” display. In such embodiments, the signal path 606 may be embodied as a wired or wireless signal path. The camera unit 604 includes two or more cameras 610, which are positioned such that reflective arrays 620 coupled to the relevant bones of a patient 612 are in the field of view 614 of the cameras 610.

The computer 600 includes a processor 622, a memory device 624, and a receiver or receiver circuitry 626. The processor 622 may be embodied as any type of processor configurable to perform the functions described herein. For example, the processor 622 may be embodied as a separate integrated circuit or as a collection of electronic devices. Additionally, the processor may be a single or multi-core processors. Although only a single processor 622 is illustrated in FIG. 28, it should be appreciated that in other embodiments, the computer 600 may include any number of additional processors. The memory device 624 may be embodied read-only memory devices and/or random access memory devices. For example, the memory device 624 may be embodied as or otherwise include electrically erasable programmable memory devices (EEPROM), dynamic random access memory devices (DRAM), synchronous dynamic random access memory devices (SDRAM), double-data rate dynamic random access memory devices (DDR SDRAM), and/or other volatile or non-volatile memory devices. Additionally, although only a single memory device is illustrated in FIG. 28, in other embodiments, the computer 600 may include additional memory devices.

The receiver circuitry 626 may be configured to use any type of wireless communication protocol, standard, or technologies to receive the joint force data from the sensor module 12. For example, as discussed above in regard to the sensor module 12, the computer 600 may be configured to communicate using a wireless networking protocol, a cellular communication protocol such as a code division multiple access (CDMA) protocol, a Bluetooth® protocol, or other wireless communication protocol, standard, or technology to communicate with the sensor module 12.

In use, the computer assisted orthopaedic surgery (CAOS) system 18 is configured to provide surgical navigation by tracking and displaying the position of the patient's relevant bony anatomy (e.g., the patient's tibia and femur) to which the reflective arrays 620 are coupled and provide an amount of surgical procedure walk-through. Additionally, the computer assisted orthopaedic surgery (CAOS) system 18 is configured to receive the joint force data from the sensor module 12 and display the joint force data or other indicia of the joint forces of the patient's joint on the display 602.

To do so, the computer 600 may execute a method 700 for performing an orthopaedic surgical procedure as illustrated in FIG. 29. The method 700 begins with block 702 in which the system 18 is initialized. For example, in block 702, the computer 600 may perform any number of system checks, clear any registers of the processor 622, and/or perform other initialization and/or integrity checks. Additionally, any number of settings, preferences, and calibrations of the CAOS system 18 may be established and performed in block 702. For example, the video settings of the display 602 may be selected, the language displayed by the computer 600 may be chosen, and the touch screen of the display device 602, if applicable, may be calibrated in block 702.

In block 704, the selections and preferences of the orthopaedic surgical procedure are chosen by the surgeon. Such selections may include the type of orthopaedic surgical procedure that is to be performed (e.g., a total knee arthroplasty), the type of orthopaedic implant that will be used (e.g., make, model, size, fixation type, etc.), the sequence of operation (e.g., the tibia or the femur first), and the like. Once the orthopaedic surgical procedure has been set up in block 704, the bones of the patient are registered in block 706. To do so, the reflective arrays 620 are coupled with the relevant bones of the patient (e.g., the tibia and femur of the patient). Additionally, the contours of such bones are registered using an appropriate registration tool. To do so, a pointer end of such tool is touched to various areas of the bones to be registered. In response to the registration, the computer 600 displays rendered images of the bones wherein the location and orientation of the bones are determined based on the reflective arrays coupled therewith and the contours of the bones are determined based on the registered points. Additionally, one or more surgical tools may be registered with the computer assisted orthopaedic surgery (CAOS) system in block 706.

Once the pertinent bones have been registered in block 706, the computer 600, in cooperation with the camera unit 604, displays the images of the surgical steps of the orthopaedic surgical procedure and associated navigation data (e.g., location of surgical tools) in block 708. To do so, the block 708 may include any number of sub-steps in which each surgical procedure step is displayed to the orthopaedic surgeon in sequential order along with the associated navigational data. Additionally, in block 710 the computer 600 receives joint force data from the sensor module 12. As discussed above, the joint force data is indicative of the joint force of the patient's knee as indicated by the sensor signals generated by the sensor array 90 of the sensor module 12.

In block 712, the computer 600 displays the joint force data or other data derived therefrom that is indicative of the joint forces of the patient's joint on the display 602. The computer 600 may be configured to determine any one or more joint force values based on the joint force data in block 712. For example, similar to the hand-held display module 14, the computer 600 may be configured to determine a medial joint force component value and a lateral joint force component value based on the joint force data received in block 710. Again, such medial joint force value is based on the sensor signals received from the pressure sensors 102, 104, 106, 108, 120, 124 and the lateral joint force value is based on the set of medial sensors 196 and the set of lateral sensors 197. In some embodiments, the computer 600 may also determine an average medial/lateral force value based on the medial joint force value and the lateral joint force value. In such embodiments, the medial joint force value, the lateral joint force value, and the average joint force value are subsequently displayed on the display 602 in block 712. In addition, the computer 600 may be configured to determine the medial-lateral and/or anterior-posterior balance of the joint forces based on the joint force data and display indicia of joint force balance on the display 602 in a manner similar to the hand-held display module 14. For example, the computer 600 may present displays similar to the displays 450, 452, 454 illustrated in and described above in regard to FIGS. 16, 17, and 18, respectively. in block 412.

In some embodiments, the computer assisted orthopaedic surgery (CAOS) system 18 may be configured to determine and display joint force data on the display 602 in association with the navigation data. For example, the computer 600 may execute a method 720 for displaying joint force data in association with navigation data as illustrated in FIG. 30. The method 720 includes a block 722 in which the computer 600 receives joint force data from the sensor module 12. Again, the joint force data is indicative of the joint force of the patient's knee as indicated by the sensor signals generated by the sensor array 90 of the sensor module 12. In block 724, the computer 600 determines the medial, lateral, and/or average joint force values based on the joint force data received in block 722.

Contemporaneously with the determination of the joint force values in block 722, the computer 600 determines the location and orientation of the patient's relevant bones, such as the patient's femur and tibia in those embodiments wherein the patient's knee is undergoing an orthopaedic surgical procedure, in block 724. Subsequently, in block 728, the computer 600 displays the joint force values determined in block 722 and the image of the knee joint in block 728. As such, the computer 600 may be used to display, for example, the flexion and extension gaps of the medial and lateral condyles of the patient's knee and contemporaneously display the associated medial, lateral, and/or average joint force values of the patient's knee. By monitoring the flexion and extension gaps and the associated joint force values, the orthopaedic surgeon may determine the appropriate amount of gap or joint force for a particular orthopaedic procedure.

Additionally, in some embodiments, the computer 600 may also be configured to determine other anatomical data based on the orientation and position of the patients bones determined in block 726 and display such anatomical data along with the associated joint force values. For example, in one embodiment, the computer 600 is configured to determine the varus/valgus angle of the patient's knee and display the associated medial and lateral force values. Additionally, the computer 600 may be configured to determine the loaded condyle based on the medial and lateral force values and identify the loaded condyle to the orthopaedic surgeon on the display 602. Further, in some embodiments, the computer 600 may be configured to store the anatomical data, the joint force values, and/or other surgical data such as the implant type size, patient identification data, and/or the like in association with each other in the memory device 624 or other storage device.

The computer 600 may also be configured to determine and display a graph of flexion angle and associated joint force values in some embodiments. To do so, the computer 600 executes a method 730 as illustrated in FIG. 31. The method 730 includes a block 732 in which the computer 600 receives joint force data from the sensor module 12. Again, the joint force data is indicative of the joint force of the patient's knee as indicated by the sensor signals generated by the sensor array 90 of the sensor module 12. In block 734, the computer 600 determines the medial, lateral, and/or average joint force values based on the joint force data received in block 732.

Contemporaneously with the determination of the joint force values in block 732, the computer 600 determines the flexion angle of the patient's knee in block 736. To do so, the computer 600 determines the relative location of the patient's tibia and femur and determines the flexion angle defined therebetween based on these locations. In block 738, the computer 600 stores the joint force data determined in block 734 and the flexion angle data determined in block 738. The method repeats through blocks 732, 734, 736 to collect data and each, or every predetermined, flexion angle within a desired range of flexion. After such data has been collected, the method 730 advances to block 740 in which the computer 600 displays a graph of joint force values versus flexion angle. Such graph may include medial and lateral joint force values or may include an average joint force values depending on the preference of the orthopaedic surgeon.

Referring now to FIGS. 32-37, as discussed above, the sensor module 12 may be used during the performance of an orthopaedic surgical procedure to monitor the relative medial-lateral balance of the patient's joint forces. For example, a surgical method 800 for performing a total knee arthroplasty procedure using the sensor module 12 is illustrated in FIG. 32. The method 800 begins with block 802 in which the proximal tibia 900 of the patient is resected. By resecting the patient's tibia 900, a resected planar surface or plateau is established on the proximal end of the tibia. In some embodiments, such as those embodiments wherein the computer assisted orthopaedic surgery (CAOS) system 18 is not used, the distal end of the patient's femur 902 may be resected in block 804.

In block 806, the patient's knee is placed in extension. Subsequently, in block 808, the patient's knee is distracted while in extension and the joint forces are balanced. To do so, the orthopaedic surgeon may place the tibial paddle 34 of the sensor module 12 in the patient's knee joint. In particular, the tibial paddle 34 is placed on the resected plateau 850 of the patient's proximal tibia as illustrated in FIG. 33. The tibial paddle 34 may be placed in contact with the patient's tibia or may be placed on a membrane or other intervening member. As shown in FIG. 33, a spacer block 832 may be used to distract the patient's knee in extension a desired amount, which may be coupled to the sensor module 12 via the upper retainer clips 516 of the adaptor 502 in some embodiments. Alternatively, the sensor module 12 may be coupled to the joint distractor 16, which may be inserted into the patient's knee joint and operated to distract the joint to the desired amount. Typically, the patient's knee joint is distracted in extension an amount necessary to establish a generally rectangular joint gap (i.e., the resected plateau 850 of the patient's tibia is approximately parallel with the resected distal end of the patient's femur).

Once a generally rectangular joint gap is established, the orthopaedic surgeon may balance the medial and lateral joint forces. To do so, the orthopaedic surgeon may perform a ligament release or balancing procedure to reduce the medial or lateral force of the patient's knee. While so doing, the orthopaedic surgeon may monitor the display 50, 52 of the sensor module 12 and/or the hand-held display module 14 to determine which side to release and when the medial and lateral forces are approximately equal (e.g., when the middle light emitting diode 84 is illuminated). Of course, the orthopaedic surgeon may decide that an alternative joint force balance, such as a 45%-55% medial-lateral joint force balance, is desirable for the particular patient based on such criteria as, for example, the age of the patient, the gender of the patient, the extent of soft tissue damage of the patient's joint, the extent of pre-operative deformity of the patient's joint, etc. Additionally, in some embodiments, such as those embodiments wherein the computer assisted orthopaedic surgery (CAOS) system 18 is used, the distal end of the patient's femur 902 may be resected in block 810.

After the orthopaedic surgeon has properly balanced the medial-lateral joint forces of the patient's joint in extension, the patient's joint is placed in flexion in block 812. Subsequently, in block 814, the patient's knee is distracted while in flexion to the desired balance of joint forces. To do so, the orthopaedic surgeon may again place the tibial paddle 34 of the sensor module 12 on the resected plateau 850 of the patient's proximal tibia 900. The tibial paddle 34 may be placed in contact with the patient's tibia or may be placed on a membrane or other intervening member. The orthopaedic surgeon may distract the patient's knee using, for example, the distractor 16, or other distractor to distract each condyle of the patient's femur differing amounts until the medial and lateral joint forces are approximately equal. By, equalizing the medial and lateral joint forces, the rotation of the femur is established.

After the patient's joint has been distracted to achieve the desired medial-lateral joint balance in block 814, a number of additional resectioning cuts are performed on the patient's distal femur 902 in block 816. To do so, as illustrated in FIG. 34, a cutting block 860 may be coupled to the joint distractor 16 and used to perform an anterior femoral cut, a posterior femoral cut, and/or chamfer cuts on the patient's distal femur 902 while the patient's joint is distracted in flexion. In one particular embodiment, the cutting block 860 is positioned such that the anterior and posterior femoral cuts are substantially parallel to the tibial cut while the patient's knee is distracted in flexion as discussed above. In other embodiments, the cutting block 860 may be positioned such that the angle of the anterior and posterior femoral cuts correspond to particular angles of the intended implant. As such, the anterior and posterior femoral cuts are performed with the femur rotated to the desired position. The position of the cutting block 860 may also be adjusted anteriorly or posteriorly to set the flexion gap for the orthopaedic implant.

Alternatively, in some embodiments, the rotation of the femur in flexion is predetermined based on anatomical references such as the posterior condyles, Whiteside's line, and/or the transepicondylar axis. The anterior femoral cut, a posterior femoral cut, and/or chamfer cuts are performed on the patient's distal femur 902 based on the predetermined rotation of the femur. As illustrated in FIG. 35, a spacer block 854 may be used to check or verify such femoral cuts. Additionally, ligamentous release may be used by the surgeon to balance or define the desired medial-lateral joint forces. In such embodiments, the orthopaedic surgeon may also verify that ligament releases performed in flexion do not adversely affect the joint force balance in extension.

After the final resectioning of the patient's distal femur is complete, the joint force balance of the patient's knee joint is verified in block 818. To do so, the orthopaedic surgeon may utilize the tibial trialing system 500 described above with regard to FIGS. 19-27. For example, as illustrated in FIGS. 36 and 37, a trialing shim 504 may be positioned over the adaptor 502 on the sensor module 12, and a tibial surface trial 505 may be secured to the trialing shim 504. A trial femoral component 864 may also be temporarily coupled to the distal end of the patient's femur 902. The patient's knee joint may then be moved through various degrees of flexion as illustrated in FIG. 37 while the orthopaedic surgeon monitors the associated joint force balance as indicated by the displays 50, 52 of the sensor module 12 or the display 302 of the display module 14 to verify that the desired joint force balance is maintained throughout flexion of the patient's joint. It should be appreciated that the trialing shim 504 may be arranged on the tibial paddle 34 of the sensor module 12 in either the fixed trialing orientation or mobile trialing orientation, as described above in regard to FIGS. 23-25. In other embodiments, a fixed or mobile tibial bearing trial 506 may be used with the adaptor 502 and sensor module 12.

The system 10 has been described above in regard to the measuring, determining, and displaying of joint forces. Such joint forces generally correspond to the joint pressure of the patient's joint over a defined area. As such, it should be appreciated that in other embodiments the sensor module 12, the hand-held display module 14, and the computer assisted surgery system 18 may be configured to measure, determine, and display the pressure of the patient's relative joint in addition to or alternatively to the patient's joint force. For example, in one embodiment, the pressure of the patient's joint may be determined based on the known area of each sensor of the pressure sensors or sensor elements 100 of the sensor array 90.

While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as illustrative and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arising from the various features of the devices, systems, and methods described herein. It will be noted that alternative embodiments of the devices, systems, and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the devices, systems, and methods that incorporate one or more of the features of the present invention and fall within the spirit and scope of the present disclosure as defined by the appended claims. 

1. An orthopaedic surgical device for measuring a joint force of a patient's joint, the orthopaedic surgical device comprising: a tibial paddle shaped to be positioned between a proximal end of a patient's tibia and a distal end of a patient's femur, the tibial paddle having a substantially planar upper surface and a substantially planar bottom surface, a sensor array positioned in the tibial paddle and configured to generate sensor signals indicative of a joint force between the patient's tibia and femur, the sensor array comprising a plurality of medial-anterior sensors to measure a medial-anterior force component of the joint force, a plurality of medial-posterior sensors to measure a medial-posterior force component of the joint force, a plurality of lateral-anterior sensors to measure a lateral-anterior force component of the joint force, and a plurality of lateral-posterior sensors to measure a lateral-posterior force component of the joint force, each of the medial-anterior sensors and lateral-anterior sensors having a substantially equal surface area and each of the medial-posterior sensors and lateral-posterior sensors having a substantially equal surface area, an elongated handle secured to the tibial paddle and defining a longitudinal axis that is offset from an anterior-to-posterior bisecting axis of the tibial paddle, a first display secured to an end of the handle distal from the tibial paddle, and a circuit positioned in the handle, the circuit configured to receive the sensor signals from the sensor array and to control the first display to provide a visual indication of the medial-lateral balance of the joint force.
 2. The orthopaedic surgical device of claim 1, wherein the tibial paddle includes a top paddle housing having a first inner sidewall that defines a first centrally-located aperture and a bottom paddle housing having a second inner sidewall that defines a second centrally-located aperture, the first aperture and second aperture being in fluid communication with each other to define, in part, a vertical passageway through the tibial paddle relative to the upper and bottom surfaces of the tibial paddle.
 3. The orthopaedic surgical device of claim 2, wherein the sensor array includes a centrally located aperture that further defines the vertical passageway through the tibial paddle.
 4. The orthopaedic surgical device of claim 1, wherein the sensor array comprises a plurality of capacitive pressure sensors.
 5. The orthopaedic surgical device of claim 1, wherein the sensor array comprises of a medial set of sensors and a lateral set of sensors, each of the medial set and lateral set of sensors consisting of an anterior-most sensor, a posterior-most sensor, and four additional sensors located between the corresponding anterior-most sensor and posterior-most sensor.
 6. The orthopaedic device of claim 1, wherein the surface area of each of the medial-anterior and lateral-anterior sensors is less than the surface area of each of the medial-posterior and lateral-posterior sensors.
 7. The orthopaedic surgical device of claim 1, wherein each of the medial-anterior and lateral-anterior sensors has a surface area equal to about 0.174 in² and each of the medial-posterior and lateral-posterior has a surface area equal to about 0.187 in².
 8. The orthopaedic surgical device of claim 1, wherein each of the medial-anterior and lateral-anterior sensors has a surface area equal to about 0.243 in² and each of the medial-posterior and lateral-posterior has a surface area equal to about 0.263 in².
 9. The orthopaedic surgical device of claim 1, further comprising a second display secured to the end of the elongated handle distal from the tibial paddle, and wherein the elongated handle comprises a top handle housing and a bottom handle housing, the top and bottom handle housings being coupled to each other such that an interior surface of the top handle housing faces a corresponding interior surface of the bottom handle housing, wherein the first display is secured to an end of the top handle housing and the second display is secured to an end of the bottom handle housing.
 10. The orthopaedic surgical device of claim 1, wherein: the first display comprises a plurality of light emitting diodes, and the circuit is configured to (i) determine a total medial force value indicative of a medial component of the joint force, (ii) determine a total lateral force value indicative of a lateral component of the joint force, and (iii) control the plurality of light emitting diodes in a manner to provide an indication of the medial-lateral balance of the joint force.
 11. The orthopaedic surgical device of claim 10, wherein the circuit is configured to control the plurality of light emitting diodes to display at least nine separate illumination configurations corresponding to nine separate medial-lateral balance ranges.
 12. The orthopaedic surgical device of claim 10, wherein the circuit is configured to: sum the total medial force value and the total lateral force value to determine a total force value, determine a medial percentage value as a function of the total medial force value and the total force value, determine a lateral percentage value as a function of the total lateral force value and the total force value, and control the plurality of light emitting diodes in a manner to provide an indication of the medial-lateral balance of the joint force as a function of the medial percentage value and the lateral percentage value.
 13. The orthopaedic surgical device of claim 1, wherein the circuit comprises a wireless transmitter configured to transmit data indicative of the joint force between the patient's tibia and femur.
 14. The orthopaedic surgical device of claim 1, wherein the circuit comprises a power source and a user control operative to place the circuit into an on-state from an off-state, wherein the circuit is configured to remain in the on-state after being placed in the on-state from the off-state until the power source is depleted. 15-20. (canceled)
 21. An orthopaedic surgical system for measuring a joint force of a patient's joint, the orthopaedic system comprising: a sensor module comprising: (i) a tibial paddle shaped to be positioned between a proximal end of a patient's tibia and a distal end of a patient's femur, the tibial paddle having a substantially planar upper surface and a substantially planar bottom surface and including an inner sidewall that defines a vertical passageway through the tibial paddle relative to the upper and bottom surfaces, (ii) a sensor array positioned in the tibial paddle and configured to generate sensor signals indicative of a joint force between the patient's tibia and femur, the sensor array comprising a plurality of medial-anterior sensors to measure a medial-anterior force component of the joint force, a plurality of medial-posterior sensors to measure a medial-posterior force component of the joint force, a plurality of lateral-anterior sensors to measure a lateral-anterior force component of the joint force, and a plurality of lateral-posterior sensors to measure a lateral-posterior force component of the joint force, each of the medial-anterior sensors and lateral-anterior sensors having a substantially equal surface area and each of the medial-posterior sensors and lateral-posterior sensors having a substantially equal surface area, (iii) an elongated handle secured to the tibial paddle, (iv) a first display secured to the handle, and (v) a sensor module circuit positioned in the handle, the sensor module circuit configured to receive the sensor signals from the sensor array, control the display to provide a visual indication of the medial-lateral balance of the joint force, and transmit the joint force data indicative of the joint force, and a hand-held display module comprising: (i) a housing sized to be hand-holdable, (ii) a display coupled to the housing, and (iii) a control circuit positioned in the housing, the control circuit configured to receive the joint force data from the sensor module and display a visual indication of the medial-lateral balance of the joint force on the display of the hand-held display module.
 22. The orthopaedic surgical system of claim 21, wherein the control circuit of the hand-held display module is configured to: display a horizontal bar on the display of the hand-held display module, display an icon on the horizontal bar, wherein the position of the icon on the horizontal bar is indicative of the medial-lateral balance of the joint force.
 23. The orthopaedic surgical system of claim 21, wherein the control circuit of the hand-held display module is configured to: determine a joint force value indicative of the medial-lateral balance and the anterior-posterior balance of the joint force, and display a visual indication on the display of the medial-lateral and the anterior-posterior balance of the joint force based on the joint force value.
 24. The orthopaedic surgical system of claim 23, wherein the control circuit of the hand-held display module is configured to display a bar on the display, the bar having a first end corresponding to a medial side and a second end corresponding to a lateral side, the control circuit being configured to position the first and second ends of the bar based on the anterior-posterior balance of the joint force.
 25. A sensor module to measure a joint force of a patient's joint, the sensor module comprising: a housing having a handle and a tibial paddle, the tibial paddle including an upper tibial plate and a lower tibial plate opposite the upper tibial plate, a sensor array positioned between the upper tibial plate and the lower tibial plate and configured to generate sensor signals indicative of a joint force between the patient's tibia and femur, the sensor array comprising a plurality of anterior sensors to measure an anterior force component of the joint force and a plurality of posterior sensors to measure a posterior component of the joint force, each of the posterior sensors having a surface area that is greater than each of the anterior sensors, a first display secured to a first surface of the housing and a second display secured to a second surface of the housing opposite the first surface, and a circuit positioned in the housing and configured to receive the sensor signals from the sensor array and to control the first and second displays to illuminate in one of a plurality of illumination configurations, each illumination configuration corresponding to a separate range of medial-lateral balance of the joint force.
 26. The orthopaedic surgical device of claim 25, wherein: the housing comprises (i) an upper housing including an upper handle housing and the upper tibial plate of the tibial paddle, and (ii) a lower housing including a lower handle housing and the lower tibial plate of the tibial paddle, the lower housing being coupled to the upper housing such that an interior surface of the lower housing faces a corresponding interior surface of the upper housing, the first display is secured to the upper handle housing and the second display is secured to the lower handle housing, and the upper tibial plate and the lower tibial plate each include an inner sidewall that defines a centrally located aperture, the inner sidewalls of the upper and lower tibial plates cooperating to define a passageway when the upper housing is coupled to the lower housing.
 27. The orthopaedic surgical device of claim 25, wherein the sensor array comprises of a medial set of sensors and a lateral set of sensors, each of the medial set and lateral set of sensors consisting of an anterior-most sensor, a posterior-most sensor, and four additional sensors located between the corresponding anterior-most sensor and posterior-most sensor.
 28. The orthopaedic surgical device of claim 25, wherein the circuit is configured to control the first and second displays to display one of a number of separate illumination configurations, wherein each illumination configurations corresponds to a separate range of medial-lateral balance of the joint force.
 29. The orthopaedic surgical device of claim 25, wherein the circuit comprises a wireless transmitter configured to transmit data indicative of the joint force between the patient's tibia and femur.
 30. The orthopaedic surgical device of claim 25, wherein the circuit comprises a power source and a user control operative to place the circuit into an on-state from an off-state, wherein the circuit is configured to remain in the on-state after being placed in the on-state from the off-state until the power source is depleted. 